Wouldn't 'Array.flat()' work instead of .reduce and .map? attempted to do it but didn't work

const users = [
    {
        name: 'Samir',
        age: 27,
        favoriteBooks: [
            {title: 'The Iliad'},
            {title: 'The Brothers Karamazov'}
        ]
    },
    {
        name: 'Angela',
        age: 33,
        favoriteBooks: [
            {title: 'Tenth of December'},
            {title: 'Cloud Atlas'},
            {title: 'One Hundred Years of Solitude'}
        ]
    },
    {
        name: 'Beatrice',
        age: 42,
        favoriteBooks: [
            {title: 'Candide'}
        ]
    }
];




//This didnt seem to work//
let iii ;

iii = users.flat(3);

console.log(iii);


//this code was for the challenge **** Please look above
// const movieTitles = users.filter( onlyTitles=> onlyTitles.favoriteBooks
//     .map( books=> books.favoriteBooks))
//     .reduce((lib, book) => [...lib,...book.favoriteBooks], [] );
//
//
// console.log(movieTitles);